Porosity particles

K" is generally known as Kozeny s constant and a commonly accepted value for K" is 5. As will be shown later, however, K" is dependent on porosity, particle shape, and other factors. Comparison with equation 4.2 shows that B the permeability coefficient is given by ... 

The presence of particles makes the effective conductivity of a gas greater than the molecular conductivity by a factor of 10 or more. The nature of the solid has little effect at Reynolds numbers above 100 or so although the effect is noticeable at the lower values of Re, it has not been completely studied. Besides the Reynolds, Prandtl, and Peclet numbers, the effective diffusivity depends on the molecular conductivity, porosity, particle size, and flow conditions. Plots in terms of Re, Pr, and Pe (without showing actual data points) are made by Beek (1962, Fig. 3), but the simpler plots obtained by a number of investigators in terms of the Reynolds number alone appear on Figure 17.36(a). As Table 17.15 shows, most of the data were obtained with air whose Pr = 0.72 and... 

When determining the physical properties of coal, there is often considerable debate about the correctness of the results obtained from measurements by two or more different analytical techniques. Provided that the methods and/or equipment used was capable of producing high-quality data, the pertinent issues relate to whether or not the sample properly prepared and properly measured and whether or not the analytical parameters applied correctly in the data-handling step(s). Thus, the concept of different techniques yielding different, albeit correct results can apply to the measurement of physical properties such as density, porosity, particle size, and surface area. 

The linear burning rate of a propellant is the velocity with which a chemical reaction progresses as a result of thermal conduction and radiation (at right angles to the current surface of the propellant). It depends on the chemical composition, the pressure, temperature and physical state of the propellant (porosity particle size distribution of the components compression). The gas (fume) cloud that is formed flows in a direction opposite to the direction of burning. 

Equation (2) is valid for surface potential of up to 50 mV. For packed capillary columns, the dependence of electroosmotic flow velocity on operating parameters based on Eq. (2) was examined and it was found that electroosmotic flow velocity increases with column porosity, particle diameter, and concentration of bulk electrolyte [21],... 

Bulk density and packed bulk (or tapped) density are important properties. The bulk density determines the weight of resin that can be stored in a vessel and the amount a mixer can hold. It also has a major influence on extruder output rates. The bulk density of a resin depends upon its porosity, particle shape and particle size distribution. For suspension resin, bulk density is typically in the range of 450-650 kg nr3. 

One of the most important requirements for the GPC column is the absence of the specific interactions with the studied polymer. The more inert the surface of the packing material, the better. Early applications of GPC separation were sometimes performed on porous glass particles with controlled porosity [9]. The ease of the manufacturing of the controlled porosity particles had determined this choice, but it was not always possible to find an... 

In both explosives and propellants the materials are relatively non-porous. The binders and plasticizers used effectively fill the pore spaces. Pyrotechnics are porous and the heat transfer related to the hot gas permeation into the reactant material mixture becomes important. In many pyrotechnics no binders or plasticizers are used. The explosives and propellants have burning (or detonation) rates that depend on density, temperature, and pressure. However, the burning rates of pyrotechnics are, in addition, affected by porosity, particle sizes, purity, homogeneity (degree of mixing), and stoichiometry (fuel or oxidizer ratio). 

Pellicular or controlled surface porosity particles were introduced in the late 1960s these have a solid inert impervious spherical core with a thin outer layer of interactive stationary phase, 1-2 pm thick [13]. Originally, the inner sphere was a glass bead, 35-50 pm i.d., with a thin active polymer film or a layer of sintered modified silica particles on its surface. Such particles were not very stable, had very low sample load capacities because of low surface areas and are not used any more. Nowadays, this type of material is available as micropellicular silica or polymer-based particles of size 1.5 to 2.5 pm [14]. Micropellicular particles are usually packed in short columns and because of fast mass-transfer kinetics have outstanding efficiency for the separation of macromolecules. Because the solutes are eluted as very sharp narrow peaks, such columns require a chromatograph designed to minimise the extra-column contributions to band broadening. 

Porosity (%) Particle diameter (pm) Mean particle dimension (pm) Coating thickness (mm)... 

Adsorbent Nature Specific surface area (m /g) Pore diameter (A) Porosity Particle density (g/cm )... 

Crysullite Size Phase Composltian Surface Area Thermostability Porosity Particle Size Density... 

In the direct input mode the user is presented with a screen with labelled blank input fields for the initial input parameters such as flow rates, mole fraction of the input stream, operating pressure, reactor parameters such as diameter, number of beds, catalyst related information, such as porosity, particle size etc. (Figure 6.25). The user has the ability to edit these values and change them at any time. Based upon the value for the number of beds in the reactor, the user is presented with another screen for the specific bed information to enter such values as bed volume and inlet temperature (Figure 6.26). 

Jackson P.D., Taylor-Smith D., Stanford RN., 1978. Resistivity-porosity-particle shape relationships for marine sands. Geophysics 43 1250-1268... 

N(P)D Neutron (Powder) Diffraction Crystalline solids Thermal neutrons E -0.0026 eV Diffracted neutrons Bulk - Crystallographic siructure porosity, particle size 44... 

Neutron (Powder) Diffraction E-0.0025 eV porosity, particle size ... 

Different properties of the prepared dry adsorbed emulsions were examined (yield value, deteiminadon of dry content, measurement of angle of repose, deter-iiiinatlou of flow rate, density, bulk density, percentage of porosity, particle size analysis. Karl Fisher titrimetry. drug release study, stability study) and the most appropriate selected for in vivo investigation. 

Seed Cultivar Moisture Content (% wb) Porosity (%) Particle Density... 

Unlike perpendicular-flow filtration where product impacts the filter head on, in cross-flow, the product approaches parallel to (tangentially) the surface. Two product streams are produced that which passes through the membrane (the permeate) and that portion which does not (retentate or concentrate). As seen below, depending on membrane porosity, particle and, eventually, molecular and ion filtration, can be achieved. 

Particle size and shape are very critical with regard to the final mechanical properties of the composite. For a medium porosity particle material, the specific surface area is in the range 3-20 m /g. Typical particle size distributions of coarse and fine products are shown in Figure 12.3. Coarser products have an average size of about 10-20 pm and top size of up to 75 pm. For the coarser grades, particle size... 

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